Underwater mobile inspection apparatus and underwater inspection equipment

ABSTRACT

An underwater mobile inspection apparatus is capable of inspecting a subsea pipeline (inspection object) while cruising. The underwater mobile inspection apparatus includes: a cruising body configured to submerge under water and cruise along the inspection object in such a manner as not to come into contact with the subsea pipeline; a first movable arm provided on the cruising body; an inspection tool unit for use in inspecting the subsea pipeline, the inspection tool unit being provided on the first movable arm; and a controller configured to, when the cruising body cruises along the subsea pipeline in such a manner as not to come into contact with the subsea pipeline, operate the first movable arm to move the inspection tool unit, such that a positional relationship of the inspection tool unit with the subsea pipeline becomes a predetermined target positional relationship.

TECHNICAL FIELD

The present invention relates to, for example, underwater mobileinspection apparatuses capable of performing various work whilecruising, including an inspection of an inspection object such as asubsea pipeline or a subsea structure, and to underwater inspectionequipment.

BACKGROUND ART

One example of a conventional underwater mobile inspection apparatus isa remotely operated underwater vehicle (see Patent Literature 1, forexample). The remotely operated underwater vehicle is configured toinspect and clean a subsea structure such as a tubular member installedon the seafloor while running on the subsea structure via casters. Anoperator can control the remotely operated underwater vehicle byoperating a ground-based control device while viewing the subseastructure from the ground via a video camera provided on the remotelyoperated underwater vehicle.

The remotely operated underwater vehicle allows the operator to operatea large number of thrusters, manipulators, and the like provided on thevehicle from the ground, and therefore, the operator can control thevehicle to move under water in a flexible manner like the operator himor herself, thereby inspecting and cleaning the subsea structure.

CITATION LIST Patent Literature

PTL 1: Japanese National Phase PCT Laid-Open Publication No. 2-503182

SUMMARY OF INVENTION Technical Problem

However, the above-described conventional remotely operated underwatervehicle has problems as follows. Since the remotely operated underwatervehicle inspects and cleans a subsea structure such as a tubular memberinstalled on the seafloor while running on the subsea structure viacasters, force based on the mass of the vehicle is applied to the subseastructure, and there is a possibility that stress due to the forcecauses damage to the subsea structure.

Further, in the case of the conventional remotely operated underwatervehicle, since the force based on the mass of the vehicle is applied tothe subsea structure, loading of, for example, devices and manipulatorsnecessary for the inspection and cleaning of the subsea structure ontothe vehicle has a certain limit in consideration of increase in theloaded mass onto the vehicle. Such limitation is an obstacle toimprovement in the quality of various work, including the inspection andcleaning of the subsea structure.

The present invention has been made to solve the above-describedproblems. An object of the present invention is to provide an underwatermobile inspection apparatus and underwater inspection equipment, whichmake it possible to prevent damage to an inspection object such as asubsea structure, the damage being due to receiving force based on themass of a cruising body, and improve the quality of various work,including an inspection of the inspection object.

Solution to Problem

An underwater mobile inspection apparatus according to the presentinvention is capable of inspecting an inspection object on a seafloorwhile cruising. The underwater mobile inspection apparatus includes: acruising body configured to submerge under water and cruise along theinspection object in such a manner as not to come into contact with theinspection object; a first movable arm provided on the cruising body; aninspection tool unit for use in inspecting the inspection object, theinspection tool unit being provided on the first movable arm; and acontroller configured to, when the cruising body cruises along theinspection object in such a manner as not to come into contact with theinspection object, operate the first movable arm to move the inspectiontool unit, such that a positional relationship of the inspection toolunit with the inspection object becomes a predetermined targetpositional relationship.

According to the underwater mobile inspection apparatus of the presentinvention, the cruising body can submerge under water and cruise alongthe inspection object in such a manner as not to come into contact withthe inspection object. At the time, the inspection tool unit provided onthe cruising body via the first movable arm can be controlled to followthe cruising body. When the cruising body cruises along the inspectionobject in such a manner as not to come into contact with the inspectionobject, the controller can operate the first movable arm to move theinspection tool unit, such that the positional relationship of theinspection tool unit with the inspection object becomes a predeterminedtarget positional relationship. This makes it possible to preciselyinspect an inspection target area of the inspection object by using theinspection tool unit.

In the underwater mobile inspection apparatus according to the presentinvention, the cruising body may include an inspection object detectorconfigured to obtain inspection object information containing apositional relationship between the cruising body and the inspectionobject and a shape of the inspection object, and the controller maycontrol the cruising body based on the inspection object information,such that the cruising body autonomously cruises along the inspectionobject in such a manner as not to come into contact with the inspectionobject.

The above configuration allows the controller to control the cruisingbody based on the inspection object information, such that the cruisingbody autonomously cruises along the inspection object in such a manneras not to come into contact with the inspection object. The inspectionobject information is information containing, for example, a positionalrelationship between the cruising body and a pipeline and the shape ofthe pipeline. Since the cruising body is configured to autonomouslycruise along the inspection object, it is not necessary toremote-control the underwater mobile inspection apparatus from anoffshore support ship, and the inspection object can be inspectedautomatically. This makes it possible to reduce labor hours, laborcosts, and costs of the support ship for inspecting the inspectionobject.

The underwater mobile inspection apparatus according to the presentinvention may include: an inspection object detector included in thecruising body and configured to obtain inspection object informationcontaining a positional relationship between the inspection tool unitand the inspection object and a shape of the inspection object; a secondmovable arm provided on the inspection tool unit; and an image-capturingcamera for use in visually inspecting the inspection object, theimage-capturing camera being provided on the second movable arm. Thecontroller may control the second movable arm based on the inspectionobject information, such that a positional relationship of theimage-capturing camera with the inspection object becomes apredetermined target positional relationship.

According to the above configuration, when the cruising body cruisesalong the inspection object in such a manner as not to come into contactwith the inspection object, the controller can operate the secondmovable arm based on the inspection object information obtained by theinspection object detector to move the image-capturing camera, such thatthe positional relationship of the image-capturing camera with theinspection object becomes a predetermined target positionalrelationship. This allows the image-capturing camera to preciselycapture an image of the external view of a predetermined target area ofthe inspection object. By visually confirming image data of the capturedimage, an operator is allowed to perform precise visual inspection of asubsea pipeline.

In the underwater mobile inspection apparatus according to the presentinvention, the inspection tool unit may include at least one of ananti-corrosion inspection device and a wall thickness inspection device.

According to the above configuration, when the underwater mobileinspection apparatus submerges under water and cruises along theinspection object in such a manner as not to come into contact with theinspection object, for example, the degree of degradation ofanti-corrosion treatment of the inspection object can be inspected byusing the anti-corrosion inspection device. In addition, the wallthickness of the inspection object can be inspected by using the wallthickness inspection device. Thus, the degree of corrosion of theinspection object and the presence or absence of damage to theinspection object can be inspected.

In the underwater mobile inspection apparatus according to the presentinvention, the anti-corrosion inspection device may include ananti-corrosion potential measurement device. The anti-corrosionpotential measurement device may include: a potential measurement probeprovided on the inspection tool unit; and a remote electrode connectedto a linear object reeled out from an electrode winch provided on thecruising body.

When the anti-corrosion potential measurement device is used as theanti-corrosion inspection device, first, the linear object is reeled outfrom the electrode winch of the cruising body by a predetermined length,and the remote electrode connected to the linear object is moved awayfrom the potential measurement probe of the inspection tool unit. Next,a potential difference between the potential measurement probepositioned near the inspection object and the remote electrode ismeasured. Based on the measured potential difference, the degree ofanti-corrosion protection (i.e., the degree of corrosion) of theinspection object can be inspected. The electrode winch for reeling inor out the linear object to which the remote electrode of theanti-corrosion potential measurement device is connected is provided onthe cruising body. Since the cruising body can cruise along theinspection object in such a manner as not to come into contact with theinspection object, damage to the inspection object due to force based onthe mass of the cruising body including the electrode winch can beprevented.

In the underwater mobile inspection apparatus according to the presentinvention, the first movable arm may include a parallel link mechanism.

The above configuration makes it possible to reduce a necessary numberof joints of the first movable arm for the controller to operate thefirst movable arm to move the inspection tool unit such that thepositional relationship of the inspection tool unit with the inspectionobject becomes a predetermined target positional relationship. As aresult, a compact and light-weight first movable arm can be provided,and also, the control of the first movable arm can be readily performed.

In the underwater mobile inspection apparatus according to the presentinvention, the inspection tool unit may be provided with a running partconfigured to allow the inspection tool unit to run on the inspectionobject, and the controller may operate the first movable arm by forcefeedback control, such that the inspection tool unit is in pressurecontact with the inspection object with predetermined target pressingforce.

According to the above configuration, the inspection tool unit can runon the inspection object while following the cruising of the cruisingbody. Since the inspection tool unit runs on the inspection object, theinspection object serves to assist in guiding the inspection tool unitto be in a predetermined target positional relationship with theinspection object. The controller is configured to operate the firstmovable arm by force feedback control, such that the inspection toolunit is in pressure contact with the inspection object withpredetermined target pressing force. Therefore, even though there is theweight of the inspection tool unit as well as inertial force exerted onthe inspection tool unit, force applied to the inspection object can becontrolled to be substantially the target pressing force. Thisconsequently makes it possible to prevent a situation where theinspection object receives the weight of the cruising body and inertialforce exerted on the cruising body and thereby becomes damaged.

In the underwater mobile inspection apparatus according to the presentinvention, the running part may be a wheel.

By thus using the wheel as the running part, the body of the inspectiontool unit can be prevented from coming into contact with the inspectionobject, and thereby damage to the inspection tool unit due to suchcontact can be prevented.

Underwater inspection equipment according to the present inventionincludes: the underwater mobile inspection apparatus according to thepresent invention; and a docking station disposed on a seafloor. Theunderwater mobile inspection apparatus is configured to be docked withand undocked from the docking station disposed on the seafloor. In astate where the underwater mobile inspection apparatus is docked withthe docking station, a first connector provided on the underwater mobileinspection apparatus is connected to a second connector provided in thedocking station, and charging of a battery of the underwater mobileinspection apparatus, transmission of inspection data that has beenobtained, or reception of an inspection instruction is performed.

According to the underwater inspection equipment of the presentinvention, after the underwater mobile inspection apparatus hasinspected the inspection object, the underwater mobile inspectionapparatus is docked with the docking station disposed on the seafloor,and the first connector of the underwater mobile inspection apparatus isconnected to the second connector of the docking station. In this state,charging of the battery of the underwater mobile inspection apparatus,transmission of inspection data that has been obtained, or reception ofan inspection instruction can be performed.

In other words, the underwater mobile inspection apparatus can transmitthe obtained inspection data to the docking station, and an operator canknow inspection results of the inspection object based on thetransmitted inspection data. Then, based on a received inspectioninstruction, the underwater mobile inspection apparatus can perform aninspection of a next inspection object. When the battery of theunderwater mobile inspection apparatus has been charged, the underwatermobile inspection apparatus can go on to the inspection of the nextinspection object while keeping staying in a submerged state at theseafloor. This makes it possible to reduce a time required forperforming the inspections and reduce labor hours.

In the underwater inspection equipment according to the presentinvention, the underwater mobile inspection apparatus may be configuredto store image data in a recording device included in the underwatermobile inspection apparatus, the image data being obtained by capturingan image of the inspection object with the image-capturing camera. In astate where the underwater mobile inspection apparatus is docked withthe docking station, the underwater mobile inspection apparatus maytransmit the image data.

According to the above configuration, when the underwater mobileinspection apparatus inspects the inspection object, the image-capturingcamera captures an image of the inspection object, and image data of thecaptured image can be stored in the recording device included in theunderwater mobile inspection apparatus. Then, in a state where theunderwater mobile inspection apparatus is docked with the dockingstation, the image data stored in the recording device can betransmitted to, for example, an offshore location.

Advantageous Effects of Invention

According to the underwater mobile inspection apparatus and underwaterinspection equipment of the present invention, the cruising body isconfigured to submerge under water and cruise along the inspectionobject in such a manner as not to come into contact with the inspectionobject. This makes it possible to prevent force based on the mass of thecruising body from being applied to the inspection object. Consequently,damage to the inspection object due to receiving force based on the massof the cruising body can be prevented. This makes it possible to performhigh-speed inspection work while cruising at a high speed.

Even if mechanical tools and devices with great mass that are necessaryfor the inspection work are loaded on the cruising body, force based onthe mass of the cruising body is not applied to the inspection object.Therefore, more mechanical tools and the like can be loaded on thecruising body compared to the conventional art. This makes it possibleto improve the quality of various work, including an inspection andcleaning of the inspection object.

The controller is configured to, when the cruising body cruises alongthe inspection object, operate the first movable arm to move theinspection tool unit, such that the positional relationship of theinspection tool unit with the inspection object becomes a predeterminedtarget positional relationship. Therefore, by means of the inspectiontool unit, an inspection of a predetermined target area of theinspection object can be precisely performed. Thus, provided is theunderwater mobile inspection apparatus, which makes it possible toimprove the quality of various work, including an inspection of theinspection object.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an enlarged side view showing an underwater mobile inspectionapparatus according to one embodiment of the present invention.

FIG. 2 is a side view showing a state where the underwater mobileinspection apparatus shown in FIG. 1 inspects an inspection object onthe seafloor.

FIG. 3A is a plan view and FIG. 3B is a side view, showing moving pathsof a cruising body and an inspection tool unit when the underwatermobile inspection apparatus shown in FIG. 1 inspects an inspectionobject on the seafloor.

FIG. 4 is a side view of underwater inspection equipment according tothe embodiment of the present invention, showing a state where theunderwater mobile inspection apparatus is docked with a docking station.

DESCRIPTION OF EMBODIMENTS

Hereinafter, one embodiment of an underwater mobile inspection apparatusand underwater inspection equipment according to the present inventionis described with reference to FIG. 1 to FIG. 4. As shown in FIG. 1, anunderwater mobile inspection apparatus 11 according to the presentembodiment is capable of, for example, performing various work whilecruising, including an inspection of an inspection object 13 such as asubsea pipeline or a subsea structure. The underwater mobile inspectionapparatus 11 makes it possible to prevent damage to the inspectionobject 13 such as a subsea structure, the damage being due to receivingforce based on the mass of a cruising body 14, and improve the qualityof various work, including the inspection of the inspection object 13.In the description below, the inspection object 13 is a subsea pipeline.

As shown in FIG. 4, underwater inspection equipment 12 according to thepresent embodiment includes the underwater mobile inspection apparatus11 and a docking station 15 disposed on the seafloor. In a state wherethe underwater mobile inspection apparatus 11 is docked with the dockingstation 15, charging of a battery of the underwater mobile inspectionapparatus 11, transmission of inspection data that has been obtained,and reception of an inspection instruction can be performed.

As shown in FIG. 1, the underwater mobile inspection apparatus 11includes the cruising body 14, a first movable arm 16, and an inspectiontool unit 17.

The cruising body 14 shown in FIG. 1 is, for example, a flatplate-shaped autonomous unmanned underwater vehicle. The cruising body14 is configured to automatically submerge under water and cruise alongthe subsea pipeline 13 in such a manner as not to come into contact withthe subsea pipeline 13 in accordance with a predetermined program. Thecruising body 14 includes: a main-propulsion thruster 18; and otherthrusters 18 for use in, for example, control of the orientation of thecruising body 14 and delicate correction of the cruising path of thecruising body 14.

The cruising body 14 includes first and second detectors 19 and 20 forobtaining inspection object information. The inspection objectinformation contains a positional relationship between the cruising body14 and the subsea pipeline 13, a positional relationship between theinspection tool unit 17 and the subsea pipeline 13, and the shape of thesubsea pipeline 13.

The first detector 19 is a multi-beam sonar. As shown in FIG. 1, thefirst detector 19 is provided at the lower front of the cruising body14. The first detector 19 mainly serves to collect inspection objectinformation regarding a forward intermediate distance range. Theinspection object information regarding the forward intermediatedistance range is information about conditions of the subsea pipeline 13and its vicinity that are an intermediate distance away, for example,the degree of bending of the subsea pipeline 13 at a forward locationthat is the intermediate distance away as well as the presence orabsence of foreign matter on the pipeline at the forward location.

The second detectors 20 are lasers for use in shape recognition. Asshown in FIG. 1, one of the second detectors 20 is disposed at the frontbottom surface of the cruising body 14 and the other second detector 20is disposed at the rear bottom surface of the cruising body 14, suchthat the second detectors 20 are spaced apart from each other. These twolasers for shape recognition mainly serve to collect inspection objectinformation regarding a forward short distance range based on adifference between their relative positions. The inspection objectinformation regarding the forward short distance range is informationabout conditions of the subsea pipeline 13 and its vicinity that are ashort distance away, for example, the degree of bending of the subseapipeline 13 at a forward location that is the short distance away aswell as the presence or absence of foreign matter on the pipeline at theforward location.

As shown in FIG. 1, the first movable arm 16 is an articulated robotarm. The proximal end of the first movable arm 16 is connected to therear of the cruising body 14, and the inspection tool unit 17 isattached to the distal end of the first movable arm 16. The firstmovable arm 16 includes first to third joints 21, 22, and 23. The firstjoint 21 is provided at the rear of the cruising body 14. A firstparallel link mechanism 24 is provided between the first joint 21 andthe second joint 22. A second parallel link mechanism 25 is providedbetween the second joint 22 and the third joint 23. The inspection toolunit 17 is provided at the third joint 23.

The first joint 21 includes a first frame 26. The first frame 26 isrotatably connected, via a vertical shaft 29, to a support protrusion 30provided at the rear of the cruising body 14. A first driver (not shown)drives the first frame 26 (first movable arm 16) to rotate around thevertical shaft 29.

The first parallel link mechanism 24 includes two parallel links 24 a.One ends of the two respective parallel links 24 a are rotatablyconnected to the first frame 26 via horizontal shafts 31. The other endsof the two respective parallel links 24 a are rotatably connected to asecond frame 27 via horizontal shafts 32. A second driver (not shown)drives the first parallel link mechanism 24 to rotate around thehorizontal shafts 31.

The second parallel link mechanism 25 includes two parallel links 25 a.On ends of the two respective parallel links 25 a are rotatablyconnected to the second frame 27 via horizontal shafts 33. The otherends of the two respective parallel links 25 a are rotatably connectedto a third frame 28 via horizontal shafts 34. A third driver (not shown)drives the second parallel link mechanism 25 to rotate around thehorizontal shafts 33.

A fourth driver (not shown) drives the inspection tool unit 17 to rotatearound a vertical shaft 52 relative to the third frame 28.

The inspection tool unit 17 is provided on the third frame 28.

As shown in FIG. 1, the inspection tool unit 17 is box-shaped. Theinspection tool unit 17 accommodates therein control devices for variousinspection devices, which will be described below. A pair of secondmovable arms 35 is provided such that the second movable arms 35 areprovided at the left and right side surfaces, respectively, of theinspection tool unit 17. First and second image-capturing cameras (e.g.,video cameras) 36 are provided on the distal ends of the pair ofrespective second movable arms 35.

The first and second image-capturing cameras 36 are configured tocapture images of the left and right side surfaces of the subseapipeline 13. The captured images allow an operator to visually inspectthe left and right side surfaces of the pipeline.

Moreover, as shown in FIG. 1, a third image-capturing camera 37 isprovided on the front surface of the inspection tool unit 17 via abracket 38. The third image-capturing camera 37 is configured to capturean image of the upper surface of the subsea pipeline 13. The capturedimage allows the operator to visually inspect the upper surface of thepipeline.

As shown in FIG. 1, the inspection tool unit 17 further includes ananti-corrosion inspection device 39 and a wall thickness inspectiondevice (not shown).

The anti-corrosion inspection device 39 serves to inspect the degree ofdegradation of anti-corrosion treatment (e.g., anti-corrosion coating)of the subsea pipeline 13 for its overall length. The anti-corrosioninspection device 39 includes a potential measurement probe 39 a and aremote electrode 39 b. The potential measurement probe 39 a is providedon the inspection tool unit 17 via the bracket 38. The distal end of thepotential measurement probe 39 a is positioned near the upper surface ofthe pipeline 13. The remote electrode 39 b is connected to the distalend of a linear object 41 which is reeled out from an electrode winch 40provided on the cruising body 14.

FIG. 1 shows a state where the anti-corrosion inspection device 39 isnot in use. In FIG. 1, the electrode winch 40 is in a state of reelingin the linear object 41, and the remote electrode 39 b is fixed to avertical tail 42 of the cruising body 14. FIG. 2 shows a state where theanti-corrosion inspection device 39 is in use. In FIG. 2, the electrodewinch 40 is in a state of reeling out the linear object 41, and theremote electrode 39 b is placed at a position that is a predetermineddistance away from the vertical tail 42 of the cruising body 14.

The wall thickness inspection device is a known conventional device, forexample, a device configured to inspect the wall thickness of the subseapipeline 13 for its overall length by using ultrasonic waves.Accordingly, the degree of corrosion of the subsea pipeline 13 and thepresence or absence of damage to the subsea pipeline 13 can beinspected.

As shown in FIG. 1, the inspection tool unit 17 is provided with arunning part 43 configured to allow the inspection tool unit 17 to runon the subsea pipeline 13 in such a manner as to contact the subseapipeline 13. The running part 43 is realized by, for example, rollingportions such as wheels. However, as an alternative, the running part 43may include not only rolling portions such as wheels but also, forexample, a sliding portion that allows the inspection tool unit 17 toslidingly move over the subsea pipeline 13.

Next, a description is given of a controller (not shown) included in thecruising body 14. The controller controls the cruising body 14 based onthe inspection object information, such that the cruising body 14autonomously cruises along the subsea pipeline 13 in such a manner asnot to come into contact with the subsea pipeline 13.

As described above, the inspection object information is obtained by thefirst and second detectors 19 and 20. The inspection object informationcontains a positional relationship between the cruising body 14 and thesubsea pipeline 13 as well as the shape of the pipeline.

The controller is configured to, when the cruising body 14 cruises basedon the inspection object information along the subsea pipeline 13 insuch a manner as not to come into contact with the subsea pipeline 13 asdescribed above, operate the first movable arm 16 based on the sameinspection object information to move the inspection tool unit 17, suchthat the positional relationship of the inspection tool unit 17 with thesubsea pipeline 13 becomes a predetermined target positionalrelationship.

Moreover, the controller is configured to operate the pair of secondmovable arms 35 shown in FIG. 1 based on the inspection objectinformation obtained by the first and second detectors 19 and 20,thereby moving the first and second image-capturing cameras 36 to theirtarget positions. Specifically, the controller operates the secondmovable arms 35 to move the first and second image-capturing cameras 36toward their target positions in accordance with, for example, thediameter of the subsea pipeline 13. That is, the controller can performautomatic correction of the positions of the first and secondimage-capturing cameras 36.

Furthermore, the controller is configured to operate the first movablearm 16 by force feedback control, such that the inspection tool unit 17,which runs on the subsea pipeline 13 shown in FIG. 1 in such a manner asto contact the subsea pipeline 13, is in pressure contact with thesubsea pipeline 13 with predetermined force. In order to realize theforce feedback control, the running part 43 (wheels) is provided with aload detector (not shown).

The load detector is configured to detect the pressure contact force ofthe inspection tool unit 17 against the subsea pipeline 13. Thecontroller is configured to control the motion of the first movable arm16, such that the detected force becomes target pressing force which isset in advance.

Next, functions of the underwater mobile inspection apparatus 11 withthe above-described configuration are described. According to theunderwater mobile inspection apparatus 11 shown in FIG. 1, in accordancewith a preset program, the cruising body 14 can submerge under water andautonomously cruise along the subsea pipeline 13 in such a manner as notto come into contact with the subsea pipeline 13. At the time, theinspection tool unit 17 provided on the cruising body 14 via the firstmovable arm 16 can be controlled to follow the cruising body 14. Dashedlines 44 shown in FIG. 3A and FIG. 3B are cruising paths of the cruisingbody 14.

Specifically, the cruising body 14 can autonomously cruise along thesubsea pipeline 13 in such a manner as not to come into contact with thesubsea pipeline 13, because, for example, a map showing the installationlocation of the subsea pipeline 13 is stored in a memory of thecontroller, and the cruising of the cruising body 14 is controlled basedon the pipeline installation location information indicated by the mapand inspection object information.

When the cruising body 14 cruises along the subsea pipeline 13 in such amanner as not to come into contact with the subsea pipeline 13, thecontroller operates the first movable arm 16 to move the inspection toolunit 17, such that the positional relationship of the inspection toolunit 17 with the subsea pipeline 13 becomes a target positionalrelationship which is set in advance.

The target positional relationship of the inspection tool unit 17 withthe subsea pipeline 13 is, as indicated by dashed lines 45 in FIG. 3Aand FIG. 3B, a positional relationship in which the inspection tool unit17 is positioned substantially right above the central axis of thesubsea pipeline 13 and runs on the subsea pipeline 13 in a state ofbeing in contact with the upper surface of the subsea pipeline 13.

As described above, the cruising body 14 is configured to submerge underwater and cruise along the subsea pipeline 13 in such a manner as not tocome into contact with the subsea pipeline 13. This makes it possible toprevent the weight of the cruising body 14 and inertial force exerted onthe cruising body 14 from being applied to the subsea pipeline 13.Consequently, damage to the subsea pipeline 13 due to receiving theweight of the cruising body 14 and the inertial force exerted on thecruising body 14 can be prevented. This makes it possible to performhigh-speed inspection work while cruising at a high speed.

Moreover, even if heavy-weight mechanical tools and devices necessaryfor the inspection work are loaded on the cruising body 14, force basedon the mass of the cruising body 14 is not applied to the subseapipeline 13. Therefore, more mechanical tools and the like can be loadedon the cruising body 14 compared to the conventional art. This makes itpossible to improve the quality of various work, including an inspectionand cleaning of the subsea pipeline 13.

Furthermore, the controller is configured to, when the cruising body 14cruises along the subsea pipeline 13, operate the first movable arm 16to move the inspection tool unit 17, such that the positionalrelationship of the inspection tool unit 17 with the subsea pipeline 13becomes a predetermined target positional relationship. Therefore, bymeans of the inspection tool unit 17, an inspection of a predeterminedtarget area of the subsea pipeline 13 (in the present embodiment, theleft side surface, the right side surface, and the upper surface of thesubsea pipeline 13 are the predetermined target area) can be preciselyperformed. Thus, provided is the underwater mobile inspection apparatus11, which makes it possible to improve the quality of various work,including an inspection and cleaning of the subsea pipeline 13.

In the present embodiment, the left side surface, the right sidesurface, and the upper surface of the subsea pipeline 13 are to beinspected. However, the inspection may be additionally performed on, forexample, the lower surface of the subsea pipeline 13.

As described above, the cruising body 14 includes the controller. Thecontroller can control the cruising body 14 based on the inspectionobject information obtained by the first and second detectors 19 and 20so that the cruising body 14 will autonomously cruise along the subseapipeline 13 in such a manner as not to come into contact with the subseapipeline 13, which is, for example, bent as shown in FIGS. 3A and 3B.

The inspection object information is information containing, forexample, a positional relationship between the cruising body 14 and thesubsea pipeline 13 as well as the shape of the pipeline 13. Theinspection object information is, for example, information about thedegree of bending of the pipeline 13 and information about the presenceor absence of foreign matter on the pipeline 13.

Since the cruising body 14 is configured to autonomously cruise alongthe subsea pipeline 13, it is not necessary to remote-control theunderwater mobile inspection apparatus 11 from an offshore support ship,and the subsea pipeline 13 can be inspected automatically. This makes itpossible to reduce labor hours, labor costs, and costs of the supportship for inspecting the subsea pipeline 13.

Further, when the cruising body 14 autonomously cruises along the subseapipeline 13 in such a manner as not to come into contact with the subseapipeline 13, the controller can operate the second movable arms 35 shownin FIG. 1 based on the inspection object information to move the firstand second image-capturing cameras 36, such that the positionalrelationship of the first and second image-capturing cameras 36 with thesubsea pipeline 13 becomes a predetermined target positionalrelationship.

The above configuration allows the first to third image-capturingcameras 36 and 37 to precisely capture images of the external view ofthe predetermined target area of the subsea pipeline 13. By visuallyconfirming image data of the captured images, an operator is allowed toperform precise visual inspection of the subsea pipeline 13.

The target positional relationship of the first and secondimage-capturing cameras 36 with the subsea pipeline 13 is, as shown inFIG. 1, a positional relationship in which the first and secondimage-capturing cameras 36 are in such positions as to be able tocapture images of the left and right side surfaces of the subseapipeline 13.

The target positional relationship of the third image-capturing camera37 with the subsea pipeline 13 is, as shown in FIG. 1, a positionalrelationship in which the third image-capturing camera 37 is in such aposition as to be able to capture an image of the upper surface of thesubsea pipeline 13.

As shown in FIG. 1, the inspection tool unit 17 includes theanti-corrosion inspection device 39 and the wall thickness inspectiondevice (not shown). Therefore, when the underwater mobile inspectionapparatus 11 submerges under water and cruises along the subsea pipeline13 in such a manner as not to come into contact with the subsea pipeline13, for example, the degree of degradation of the anti-corrosiontreatment (e.g., anti-corrosion coating) of the subsea pipeline 13 canbe automatically inspected by using the anti-corrosion inspection device39. In addition, the wall thickness of the subsea pipeline 13 can beautomatically inspected by using the wall thickness inspection device.Thus, the degree of corrosion of the subsea pipeline 13 and the presenceor absence of damage to the subsea pipeline 13 can be inspected.

When an anti-corrosion potential measurement device is used as theanti-corrosion inspection device 39 as shown in FIG. 2, first, thelinear object 41 is reeled out from the electrode winch 40 of thecruising body 14 by a predetermined length, and the remote electrode 39b connected to the linear object 41 is moved away from the potentialmeasurement probe 39 a of the inspection tool unit 17 by a predetermineddistance. Next, a potential difference between the potential measurementprobe 39 a positioned near the subsea pipeline 13 and the remoteelectrode 39 b is measured. Based on the measured potential difference,the degree of the anti-corrosion protection (i.e., the degree ofcorrosion) of the subsea pipeline 13 can be inspected.

The electrode winch 40 for reeling in or out the linear object 41 towhich the remote electrode 39 b of the anti-corrosion inspection device39 is connected is provided on the cruising body 14. Since the cruisingbody 14 can cruise along the subsea pipeline 13 in such a manner as notto come into contact with the subsea pipeline 13, damage to the subseapipeline 13 due to force based on the mass of the cruising body 14including the electrode winch 40 can be prevented.

Further, as shown in FIG. 1, the first movable arm 16 includes the firstand second parallel link mechanisms 24 and 25. This makes it possible toreduce a necessary number of joints of the first movable arm 16 for thecontroller to operate the first movable arm 16 to move the inspectiontool unit 17 such that the positional relationship of the inspectiontool unit 17 with the subsea pipeline 13 becomes a predetermined targetpositional relationship. As a result, a compact and light-weight firstmovable arm 16 can be provided, and also, the control of the firstmovable arm 16 can be readily performed.

As shown in FIG. 1, the inspection tool unit 17 is provided with therunning part 43 (wheels), which allows the inspection tool unit 17 torun on the subsea pipeline 13. Accordingly, the inspection tool unit 17can run on the subsea pipeline 13 while following the cruising of thecruising body 14. Since the inspection tool unit 17 runs on the subseapipeline 13, the subsea pipeline 13 serves to assist in guiding theinspection tool unit 17 to be in a predetermined target positionalrelationship with the subsea pipeline 13.

The controller is configured to operate the first movable arm 16 byforce feedback control, such that the inspection tool unit 17 is inpressure contact with the subsea pipeline 13 with predetermined force.Therefore, even though there is the weight of the inspection tool unit17 as well as inertial force exerted on the inspection tool unit 17,force applied to the subsea pipeline 13 can be controlled to bepredetermined target pressing force. This consequently makes it possibleto prevent a situation where the subsea pipeline 13 receives force basedon the mass of the cruising body 14 and thereby becomes damaged.

Further, by using wheels as the running part 43 of the inspection toolunit 17, the body of the inspection tool unit 17 can be assuredlyprevented from coming into contact with the subsea pipeline 13, andthereby damage to the inspection tool unit 17 due to such contact can beprevented.

Next, the underwater inspection equipment 12 is described with referenceto FIG. 4. The underwater inspection equipment 12 shown in FIG. 4includes the underwater mobile inspection apparatus 11 and the dockingstation 15 disposed on the seafloor.

The docking station 15 includes a substantially parallelepiped cage-likeunit 46. The underwater mobile inspection apparatus 11 enters the insideof the cage-like unit 46 where the underwater mobile inspectionapparatus 11 can be docked. A second connector 48 is provided on a floor46 a of the cage-like unit 46.

As shown in FIG. 4, the underwater mobile inspection apparatus 11 can bedocked with and undocked from the docking station 15 disposed on theseafloor. In a state where the underwater mobile inspection apparatus 11is docked with the docking station 15, a first connector 47 provided onthe underwater mobile inspection apparatus 11 is connected to the secondconnector 48 provided in the docking station 15 so that charging of abattery included in the cruising body 14 of the underwater mobileinspection apparatus 11, transmission of inspection data that has beenobtained, and reception of an inspection instruction can be performed.

For example, the docking station 15 is suspended by a rope 49 from anoffshore production base. The rope 49 is reeled in or out by a hoist(not shown). Accordingly, the docking station 15 is lifted and loweredby the hoist, and thereby the docking station 15 can be drawn up ontothe offshore production base or set on a seafloor 50.

The offshore production base and the docking station 15 are connected toeach other by a cable 51. Via the cable 51, electric power for use incharging the battery can be supplied, and an inspection instruction canbe transmitted, from the offshore production base to the docking station15. Moreover, inspection data obtained by the underwater mobileinspection apparatus 11 can be transmitted from the docking station 15to the offshore production base via the cable 51. The second connector48 of the docking station 15 is connected to the cable 51. The offshoreproduction base is, for example, a petroleum gas production rig or afloating crude oil production, storage and offloading facility.

According to the underwater inspection equipment 12 shown in FIG. 4,after the underwater mobile inspection apparatus 11 has inspected thesubsea pipeline 13, the underwater mobile inspection apparatus 11 isdocked with the docking station 15 disposed on the seafloor 50, and thefirst connector 47 of the underwater mobile inspection apparatus 11 isconnected to the second connector 48 of the docking station 15. In thisstate, charging of the battery of the underwater mobile inspectionapparatus 11, transmission of inspection data that has been obtained,and reception of an inspection instruction can be performed.

In other words, the underwater mobile inspection apparatus 11 cantransmit the obtained inspection data to the offshore production basevia the docking station 15, and an operator can know inspection resultsof the subsea pipeline 13 based on the transmitted inspection data.Then, based on a received inspection instruction, the underwater mobileinspection apparatus 11 can perform an inspection of, for example, anext subsea pipeline 13. When the battery of the underwater mobileinspection apparatus 11 has been charged, the underwater mobileinspection apparatus 11 can go on to the inspection of, for example, thenext subsea pipeline 13 while keeping staying in a submerged state atthe seafloor. This makes it possible to reduce a time required forperforming the inspections and reduce labor hours.

The underwater mobile inspection apparatus 11 included in the underwaterinspection equipment 12 shown in FIG. 4 is configured to storeinspection data in a recording device (not shown) included in thecruising body 14 of the underwater mobile inspection apparatus 11, theinspection data containing image data that is obtained by capturingimages of the subsea pipeline 13 with the first to third image-capturingcameras 36 and 37. In a state where the underwater mobile inspectionapparatus 11 is docked with the docking station 15, or after theunderwater mobile inspection apparatus 11 is docked with the dockingstation 15, the inspection data containing the image data can betransmitted to the offshore production base via the cable 51 of thedocking station 15.

According to the underwater inspection equipment 12, when the underwatermobile inspection apparatus 11 inspects the subsea pipeline 13, thefirst to third image-capturing cameras 36 and 37 capture images of thesubsea pipeline 13, and inspection data containing image data of thecaptured images can be stored in the recording device included in theunderwater mobile inspection apparatus 11. Then, in a state where theunderwater mobile inspection apparatus 11 is docked with the dockingstation, or after the underwater mobile inspection apparatus 11 isdocked with the docking station, the inspection data stored in therecording device, which contains the image data, can be transmitted to,for example, an offshore location via the cable 51.

Although the above embodiment has been described by taking a subseapipeline as an example of the inspection object 13, the inspectionobject 13 is not limited to a subsea pipeline, but may be, for example,a submarine electrical cable laid on the seafloor or a subsea structuresuch as a jacket.

In the above-described embodiment, the underwater mobile inspectionapparatus 11 cruises along the subsea pipeline 13, and while cruising,inspects the subsea pipeline 13 by means of the inspection tool unit 17.However, as an alternative, the underwater mobile inspection apparatus11 may inspect a facility or a building built on the seafloor.

Further, in the above-described embodiment, as shown in FIG. 1, theinspection tool unit 17 is provided with the wheels 43. The inspectiontool unit 17 inspects the subsea pipeline 13 while running on the subseapipeline 13 in such a manner as to contact the subsea pipeline 13 viathe wheels 43. However, the inspection tool unit 17 need not be providedwith the wheels 43, and the inspection tool unit 17 may inspect thesubsea pipeline 13 while moving along the subsea pipeline 13 in such amanner as not to come into contact with the subsea pipeline 13.

Also in this case, the controller is configured to control the firstmovable arm 16 such that the positional relationship of the inspectiontool unit 17 with the subsea pipeline 13 becomes a predetermined targetpositional relationship.

If the inspection tool unit 17 performs the inspection of the subseapipeline 13 in such a non-contact manner as above, a situation where thesubsea pipeline 13 receives the weight of the inspection tool unit 17and inertial force exerted on the inspection tool unit 17 and therebybecomes damaged can be prevented. This makes it possible to performfaster inspection work by faster cruising.

Further, in the above-described embodiment, the cruising body 14 is notremote-controlled but cruises autonomously. However, as an alternative,a cable may be connected to the cruising body, and an operator mayremote-control the cruising body via the cable from an offshore locationor from the ground to inspect the subsea pipeline 13.

INDUSTRIAL APPLICABILITY

As described above, the underwater mobile inspection apparatus andunderwater inspection equipment according to the present invention makeit possible to prevent damage to an inspection object such as a subseastructure, the damage being due to receiving force based on the mass ofthe cruising body, and provide an excellent advantage of improving thequality of various work, including an inspection of the inspectionobject. Thus, the present invention is suitably applicable to underwatermobile inspection apparatuses and underwater inspection equipment.

REFERENCE SIGNS LIST

11 underwater mobile inspection apparatus

12 underwater inspection equipment

13 inspection object (subsea pipeline)

14 cruising body

15 docking station

16 first movable arm

17 inspection tool unit

18 thruster

19 first detector

20 second detector

21 first joint

22 second joint

23 third joint

24 first parallel link mechanism

24 a parallel link

25 second parallel link mechanism

25 a parallel link

26 first frame

27 second frame

28 third frame

29 vertical shaft

30 support protrusion

31, 32, 33, 34 horizontal shaft

35 second movable arm

36 first and second image-capturing cameras

37 third image-capturing camera

38 bracket

39 anti-corrosion inspection device

39 a potential measurement probe

39 b remote electrode

40 electrode winch

41 linear object

42 vertical tail

43 running part (wheels)

44 dashed line indicating a cruising path

45 dashed line indicating a running path

46 cage-like unit

46 a floor

47 first connector

48 second connector

49 rope

50 seafloor

51 cable

52 vertical shaft

1. An underwater mobile inspection apparatus capable of inspecting aninspection object on a seafloor while cruising, the underwater mobileinspection apparatus comprising: a cruising body configured to submergeunder water and cruise along the inspection object in such a manner asnot to come into contact with the inspection object; a first movable armprovided on the cruising body; an inspection tool unit for use ininspecting the inspection object, the inspection tool unit beingprovided on the first movable arm; and a controller configured to, whenthe cruising body cruises along the inspection object in such a manneras not to come into contact with the inspection object, operate thefirst movable arm to move the inspection tool unit, such that apositional relationship of the inspection tool unit with the inspectionobject becomes a predetermined target positional relationship.
 2. Theunderwater mobile inspection apparatus according to claim 1, wherein thecruising body includes an inspection object detector configured toobtain inspection object information containing a positionalrelationship between the cruising body and the inspection object and ashape of the inspection object, and the controller controls the cruisingbody based on the inspection object information, such that the cruisingbody autonomously cruises along the inspection object in such a manneras not to come into contact with the inspection object.
 3. Theunderwater mobile inspection apparatus according to claim 1, comprising:an inspection object detector included in the cruising body andconfigured to obtain inspection object information containing apositional relationship between the inspection tool unit and theinspection object and a shape of the inspection object; a second movablearm provided on the inspection tool unit; and an image-capturing camerafor use in visually inspecting the inspection object, theimage-capturing camera being provided on the second movable arm, whereinthe controller controls the second movable arm based on the inspectionobject information, such that a positional relationship of theimage-capturing camera with the inspection object becomes apredetermined target positional relationship.
 4. The underwater mobileinspection apparatus according to claim 1, wherein the inspection toolunit includes at least one of an anti-corrosion inspection device and awall thickness inspection device.
 5. The underwater mobile inspectionapparatus according to claim 4, wherein the anti-corrosion inspectiondevice includes an anti-corrosion potential measurement device, and theanti-corrosion potential measurement device includes: a potentialmeasurement probe provided on the inspection tool unit; and a remoteelectrode connected to a linear object reeled out from an electrodewinch provided on the cruising body.
 6. The underwater mobile inspectionapparatus according to claim 1, wherein the first movable arm includes aparallel link mechanism.
 7. The underwater mobile inspection apparatusaccording to claim 1, wherein the inspection tool unit is provided witha running part configured to allow the inspection tool unit to run onthe inspection object, and the controller operates the first movable armby force feedback control, such that the inspection tool unit is inpressure contact with the inspection object with predetermined targetpressing force.
 8. The underwater mobile inspection apparatus accordingto claim 7, wherein the running part is a wheel.
 9. Underwaterinspection equipment comprising: the underwater mobile inspectionapparatus according to claim 1; and a docking station disposed on aseafloor, wherein the underwater mobile inspection apparatus isconfigured to be docked with and undocked from the docking stationdisposed on the seafloor, and in a state where the underwater mobileinspection apparatus is docked with the docking station, a firstconnector provided on the underwater mobile inspection apparatus isconnected to a second connector provided in the docking station, andcharging of a battery of the underwater mobile inspection apparatus,transmission of inspection data that has been obtained, or reception ofan inspection instruction is performed.
 10. The underwater inspectionequipment according to claim 9, comprising an underwater mobileinspection apparatus including: an inspection object detector includedin the cruising body and configured to obtain inspection objectinformation containing a positional relationship between the inspectiontool unit and the inspection object and a shape of the inspection objecta second movable arm provided on the inspection tool unit and animage-capturing camera for use in visually inspecting the inspectionobject, the image-capturing camera being provided on the second movablearm, wherein the controller controls the second movable arm based on theinspection object information, such that a positional relationship ofthe image-capturing camera with the inspection object becomes apredetermined target positional relationship; wherein the underwatermobile inspection apparatus is configured to store image data in arecording device included in the underwater mobile inspection apparatus,the image data being obtained by capturing an image of the inspectionobject with the image-capturing camera, and in a state where theunderwater mobile inspection apparatus is docked with the dockingstation, the underwater mobile inspection apparatus transmits the imagedata.
 11. The underwater mobile inspection apparatus according to claim2, comprising: an inspection object detector included in the cruisingbody and configured to obtain inspection object information containing apositional relationship between the inspection tool unit and theinspection object and a shape of the inspection object; a second movablearm provided on the inspection tool unit; and an image-capturing camerafor use in visually inspecting the inspection object, theimage-capturing camera being provided on the second movable arm, whereinthe controller controls the second movable arm based on the inspectionobject information, such that a positional relationship of theimage-capturing camera with the inspection object becomes apredetermined target positional relationship.